Elektor Electronics

[Eric]

Anyone get Elektor Electronics magazine
http://213.222.12.205/Default.aspx?tabid=27&year=2005&month=9&art=52895&PN=O
n

Hopeless NZ bookshops have not put it on the shelf yet,

Does anyone know what capacitors range the ESR meter does?

 

[Phil Allison]

"Eric the Kiwi"

Anyone get Elektor Electronics magazine

** A waste of perfectly good trees.

Hopeless NZ bookshops have not put it on the shelf yet,

** Trees 1, Elektor 0.

Does anyone know what capacitors range the ESR meter does?

** Who bloody cares ??

Every second DMM on sale measures capacitance well enough.

For PSU electros an ESR meter is all you need and Bob Parker's one is a
winner.

If an electro passes the ESR test - then it has its original (marked)
capacitance value.

If an electro fails the ESR test - then it goes straight in the bin.


Capice ?




.......... Phil

 

[The Real Andy]

On Sun, 11 Sep 2005 13:11:45 +1000, "Phil Allison"
<philallison@tpg.com.au> wrote:

"Eric the Kiwi"

Anyone get Elektor Electronics magazine

** A waste of perfectly good trees.

Why is that Phil? Is it because the dont publish designs based on
pre-historic components?

Perhaps the ex roadies dont like mags that publish mostly digital
designs

<snip>

 

[Tom]

The Real Andy wrote:

On Sun, 11 Sep 2005 13:11:45 +1000, "Phil Allison"
philallison@tpg.com.au> wrote:


"Eric the Kiwi"


Anyone get Elektor Electronics magazine

** A waste of perfectly good trees.



Why is that Phil? Is it because the dont publish designs based on
pre-historic components?

Because you can get same thing in a pdf

 

[Eric]

Now why did I think as I wrote the question, "I would most unlikely get a
answer, just pathic replys from children that have nothing better to do"

 

[Phil Allison]

"Eric"

Now why did I think as I wrote the question, "I would most unlikely get a
answer, just pathic replys from children that have nothing better to do"

** YOU are a fucking, PITA **TROLL** - eric.


Go check the Auckland phone book for typos - if you can stand the
excitement.





........... Phil

 

[Franc Zabkar]

On Sun, 11 Sep 2005 08:42:14 +1200, "Eric" <eric@home.net> put finger
to keyboard and composed:

Anyone get Elektor Electronics magazine
http://213.222.12.205/Default.aspx?tabid=27&year=2005&month=9&art=52895&PN=O
n

Hopeless NZ bookshops have not put it on the shelf yet,

Does anyone know what capacitors range the ESR meter does?

With respect, I can't see that this question makes any sense. An ESR
meter measures ESR, not capacitance. Ideally the capacitor's C should
not affect the result because it should look like a S/C to the test
signal.

I don't know anything about the Elektor meter, but Bob Parker's meter
applies charging pulses of three different amplitudes to the capacitor
under test, and then compares the voltage to an internal reference
capacitor. The assumption is that the pulse is of sufficently short
duration so as not to appreciably charge the test capacitor. AFAICS,
the larger the cap, the more accurate the measurement. As for very
small caps, I would think that the meter's internal time constants
would be selected so as to accommodate the smallest expected values of
capacitance. At the very worst, the meter would overestimate the ESR.
In this case the user could check the reading against a known good cap
of the same value.

-- Franc Zabkar

Please remove one 'i' from my address when replying by email.

 

[The Real Andy]

On Tue, 13 Sep 2005 20:16:41 +1000, "Phil Allison"
<philallison@tpg.com.au> wrote:

"Eric"

Now why did I think as I wrote the question, "I would most unlikely get a
answer, just pathic replys from children that have nothing better to do"



** YOU are a fucking, PITA **TROLL** - eric.


Go check the Auckland phone book for typos - if you can stand the
excitement.





.......... Phil

For an individual with such a pathetic existance, you still manage to

extract a chuckle from me phil...

 

[The Real Andy]

On Tue, 13 Sep 2005 06:23:05 +1200, "Eric" <eric@home.net> wrote:

Now why did I think as I wrote the question, "I would most unlikely get a
answer, just pathic replys from children that have nothing better to do"

This is aus.e;ectronics, and it does reflect the nature of the
industry in australia

I used to be an elektor subscriber and they continue to send me mags.
If this one turns up in the post I will email you.

 

[quietguy]

Looking at a review of ESR meters I note that they do vary in respect of the
range of caps they can accurately check for ESR - especially at the lower end of
the range I gather

David

Franc Zabkar wrote:

On Sun, 11 Sep 2005 08:42:14 +1200, "Eric" <eric@home.net> put finger
to keyboard and composed:

Does anyone know what capacitors range the ESR meter does?

With respect, I can't see that this question makes any sense. An ESR
meter measures ESR, not capacitance. Ideally the capacitor's C should
not affect the result because it should look like a S/C to the test
signal.

 

[Franc Zabkar]

On Wed, 14 Sep 2005 23:57:28 GMT, quietguy
<quietguy@REMOVE-TO-REPLYconfidential-counselling.com> put finger to
keyboard and composed:

Looking at a review of ESR meters I note that they do vary in respect of the
range of caps they can accurately check for ESR - especially at the lower end of
the range I gather

David

Well, that's what I expected in the worst case.

Anyway, I notice that the ESR table on Bob Parker's Mark 1 meter goes
down to 1uF, so I tried the following test using five Hitano EXR
series 105 degC 1uF 100V low ESR electrolytics (WES code 1EXR100).

individual ESR measurements (1uF): 3.1, 3.3, 3.6, 3.8, 3.8 ohms
all five in series (0.2uF): 18 ohms
all five in parallel (5uF): 0.67 ohms

The results suggest that the meter is reasonably linear in the range
0.2uF - 5uF.

The next readings are for used, 250V, film, mains rated X2 caps:

C (uF) ESR (ohms)
-----------------------
1.0 1.4 1.4
0.82 1.5 1.5
0.47 3.3 2.9 3.5
0.22 7.7
0.10 19 19

I would have thought that the ESR for this type of cap was negligible
(< 0.5 ohm ???). If so, then the readings must reflect the
capacitance's contribution to the measurement process. If I understand
Bob's design correctly, the capacitance should contribute a
"resistance" value of dt/C (= dV/Ipulse), where dt is the duration of
the charging pulse. For example, a 1us pulse into an ideal 1uF cap
should make it test like a 1 ohm resistance, whereas an 0.1uF cap
would measure 10 ohms.

Franc Zabkar wrote:

On Sun, 11 Sep 2005 08:42:14 +1200, "Eric" <eric@home.net> put finger
to keyboard and composed:

Does anyone know what capacitors range the ESR meter does?

With respect, I can't see that this question makes any sense. An ESR
meter measures ESR, not capacitance. Ideally the capacitor's C should
not affect the result because it should look like a S/C to the test
signal.

-- Franc Zabkar

Please remove one 'i' from my address when replying by email.

 

[Phil Allison]

"Franc Zabkar"
quietguy

Looking at a review of ESR meters I note that they do vary in respect of
the
range of caps they can accurately check for ESR - especially at the lower
end of
the range I gather


Anyway, I notice that the ESR table on Bob Parker's Mark 1 meter goes
down to 1uF, so I tried the following test using five Hitano EXR
series 105 degC 1uF 100V low ESR electrolytics (WES code 1EXR100).

individual ESR measurements (1uF): 3.1, 3.3, 3.6, 3.8, 3.8 ohms
all five in series (0.2uF): 18 ohms
all five in parallel (5uF): 0.67 ohms

The results suggest that the meter is reasonably linear in the range
0.2uF - 5uF.

The next readings are for used, 250V, film, mains rated X2 caps:

C (uF) ESR (ohms)
-----------------------
1.0 1.4 1.4
0.82 1.5 1.5
0.47 3.3 2.9 3.5
0.22 7.7
0.10 19 19

I would have thought that the ESR for this type of cap was negligible
(< 0.5 ohm ???). If so, then the readings must reflect the
capacitance's contribution to the measurement process. If I understand
Bob's design correctly, the capacitance should contribute a
"resistance" value of dt/C (= dV/Ipulse), where dt is the duration of
the charging pulse. For example, a 1us pulse into an ideal 1uF cap
should make it test like a 1 ohm resistance, whereas an 0.1uF cap
would measure 10 ohms.

** Bob's brilliant ESR meter is very clearly intended to test ** ELECTROS
** - while in circuit, in faulty gear !!

The whole reason for testing the electros is because at the end of their
useful life, the " juice " inside dries out sending the ESR value high.

The principle of operation relies on the fact that at a frequency of about
100kHz, an electro's impedance it at its minimum value - so nearly equal
to the intrinsic internal resistance or ESR !!

Very low value electros, like 1 uF, need a slightly higher test frequency
for best accuracy.

However, plastic film capacitors need to be tested from 1 to 10 MHz to find
their true ESR values - only a variable frequency ESR meter could do that
as you need to find the series resonance .

Film caps do not vary in ESR throughout their life - so no need for such
testing exists.





.......... Phil

 

[S Roby]

In article <p93ii1949lbn0j81ulijl8ujrs3bdbb196@4ax.com>, fzabkar@iinternode.on.net wrote:

On Wed, 14 Sep 2005 23:57:28 GMT, quietguy
quietguy@REMOVE-TO-REPLYconfidential-counselling.com> put finger to
keyboard and composed:

Looking at a review of ESR meters I note that they do vary in respect of the
range of caps they can accurately check for ESR - especially at the lower end
of
the range I gather

David

Well, that's what I expected in the worst case.

Anyway, I notice that the ESR table on Bob Parker's Mark 1 meter goes
down to 1uF, so I tried the following test using five Hitano EXR
series 105 degC 1uF 100V low ESR electrolytics (WES code 1EXR100).

Ive tested faulty electro caps which still give a 'pass' according to the
table. Ive also got some caps quite visibly leaking & buldging that test
'ok 'with my ESR & a CAP meter.
Just something to bear in mind for amatures (like me).

 

[S Roby]

In article <3ov8jtF7ru5hU1@individual.net>, "Phil Allison" <philallison@tpg.com.au> wrote:

"S Roby"


Ive tested faulty electro caps which still give a 'pass' according to the
table.

** What make you sure they were faulty then ??

The tech at work pulled them out(replaced them) to fix power supplies.

 

[Phil Allison]

"S Roby"

Ive tested faulty electro caps which still give a 'pass' according to the
table.

** What make you sure they were faulty then ??

I've also got some caps quite visibly leaking & buldging that test
'ok 'with my ESR & a CAP meter.

** So they were electrically OK - but visual reasons existed to replace
them .





.............. Phil

 

[Phil Allison]

"S Roby"
"Phil Allison"

Ive tested faulty electro caps which still give a 'pass' according to
the
table.

** What make you sure they were faulty then ??


The tech at work pulled them out(replaced them) to fix power supplies.

** I repeat:

What make you sure they were faulty then ??

The tech may have replaced them as a precaution or because they were of a
certain age etc.



............ Phil

 

[Bob Parker]

ESR meters aren't some kind of mystical box which magically tell
you with 100% accuracy which capacitors are defective. They're just
one more test instrument which tells an experienced user with a good
knowledge of electronics about another characteristic of capacitors
which is very relevant to how well they're doing their job. ESR meter
readings have to be intelligently combined with other factors
including the physical state of the capacitor being tested.
I never cease to be amazed by how little electrical knowledge many
ESR meter users have. The DSE meter was designed specifically for
service technicians, but many of them have been bought by hobbisyts
and "amatures", a lot of whom still seem to think that ESR equates to
leakage and/or that the higher the ESR the better.
I agree with Phil's comments... he understands and appreciates
where ESR meters fit into the overall scheme of things.
That's my 2c worth.

Cheers
Bob


On Fri, 16 Sep 2005 17:43:49 +1000, "Phil Allison"
<philallison@tpg.com.au> wrote:

"S Roby"
"Phil Allison"

Ive tested faulty electro caps which still give a 'pass' according to
the
table.

** What make you sure they were faulty then ??


The tech at work pulled them out(replaced them) to fix power supplies.



** I repeat:

What make you sure they were faulty then ??

The tech may have replaced them as a precaution or because they were of a
certain age etc.



........... Phil

 

[Franc Zabkar]

On Thu, 15 Sep 2005 18:41:49 +1000, "Phil Allison"
<philallison@tpg.com.au> put finger to keyboard and composed:

The principle of operation relies on the fact that at a frequency of about
100kHz, an electro's impedance it at its minimum value - so nearly equal
to the intrinsic internal resistance or ESR !!

The test signal is not sinusoidal. While the Xc of a 1uF cap at 100kHz
is a negligible 1.6 ohms, that is not what the meter sees. The test
signal, at least for the Mark 2 version, is an 8us current pulse with
a frequency of 2kHz. The voltage seen at the meter's terminals would
be given by ...

V = (I * R) + (I * dt/C)

The meter assumes it is seeing a pure resistance (R'), so it applies
Ohm's Law and comes up with ...

R' = V/I
= R + dt/C

This reduces to R' = R + 8 in the above case.

So if one were to apply the design principle described by Bob in his
SC article, one would expect the meter to read 8 ohms for a perfect
1uF capacitance. This is not what I observe in practice, but it may at
least partly explain the higher than expected readings for the film
caps.

-- Franc Zabkar

Please remove one 'i' from my address when replying by email.

 

[Franc Zabkar]

On Thu, 15 Sep 2005 18:41:49 +1000, "Phil Allison"
<philallison@tpg.com.au> put finger to keyboard and composed:

"Franc Zabkar"

The next readings are for used, 250V, film, mains rated X2 caps:

C (uF) ESR (ohms)
-----------------------
1.0 1.4 1.4
0.82 1.5 1.5
0.47 3.3 2.9 3.5
0.22 7.7
0.10 19 19

I would have thought that the ESR for this type of cap was negligible
(< 0.5 ohm ???). If so, then the readings must reflect the
capacitance's contribution to the measurement process.

However, plastic film capacitors need to be tested from 1 to 10 MHz to find
their true ESR values - only a variable frequency ESR meter could do that
as you need to find the series resonance .

Film caps do not vary in ESR throughout their life - so no need for such
testing exists.

I did not suggest that such testing was required. I merely wanted to
see how the meter would evaluate "perfect" caps. To paraphrase Dirty
Harry, a man's gotta know his test equipment's limitations.

Regardless, manufacturers quote a loss tangent figure for these types
of caps.

See this datasheet:
http://www.vishay.com/docs/28119/mkp3382.pdf

Tangent of loss angle at 1 kHz 10 kHz 100 kHz
----------------------------------------------------
C <= 470 nF 0.001 0.002 0.010

The loss tangent is given by:

tan d = 2pi * f * C * R

So R (in ohms) in the above three cases for an 0.47uF film cap is as
follows:

R at 1 kHz 10 kHz 100 kHz
---------------------------------
0.34 0.068 0.034


-- Franc Zabkar

Please remove one 'i' from my address when replying by email.

 

[S Roby]

** I repeat:

What make you sure they were faulty then ??

I repeat
The tech at work pulled them out(replaced them) to fix power supplies.

The power supplies had spikes on the output (clearly seen on the scope) ,
fixed by replacing caps.